We propose to investigate in detail the mechanisms by which an insulin receptor appears on the surface of activated lymphocytes and the biologic properties of this receptor utilizing the microfuge insulin binding assay. The appearance of an insulin receptor upon the surface of alloimmune cytotoxic T lymphocytes permits the induction of immunopotentiation by physiologic concentrations of insulin. The identities of other insulin receptor positive lymphocyte subpopulations will be studied and the role of the insulin and receptor interaction during the differentiation and effector function of these cells will be elucidated. The physiochemical properties of the receptor and the intracellular events triggered by the hormone and receptor interaction will be investigated. It is likely that the appearance and disappearance of the receptor provide a unique feedback loop on lymphocyte function. This hypothesis and the possibility that insulin may provide a physiologic tool for clinical immunopotentiation will be tested.